Apparatus for generating inductively coupled plasma

ABSTRACT

Disclosed is an apparatus for generating ICP, which has a heater having a hot wire as a heating source for heating elements in a chamber and inner wall of the chamber and also efficiently transfers heat of the heater through a heat transferring gas to the elements in the chamber and the inner wall of the chamber. According to the present invention, the elements in the chamber and the inner wall of the chamber can be heated up to a temperature of about 200° C., thereby reducing the adhesion of the by-product served as the source generating the undesirable particles. In addition, since the hot wire having a longer life span than the halogen lamp is used as heat radiating means, the life span of the apparatus is also increased.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an apparatus for generating ICP(inductively coupled plasma), and more particularly, to an apparatus forgenerating ICP, enabling to reduce occurrence of undesirable particles.

[0003] 2. Description of the Related Art

[0004] Semiconductor processing equipments using plasma are generallyclassified into etching equipment and depositing equipment. When asemiconductor process is performed in the semiconductor processingequipment, by-products are inevitably adhered to elements and inner wallof a chamber. The adhered by-product acts as a source that generatesundesirable particles during the semiconductor process, therebydegenerating the productivity.

[0005] In order to restrain the generation of the particles, theadhesion of the by-product has to be restrained. Further, in order torestrain the adhesion of the by-product, there is used a method ofheating the elements or the inner wall of the chamber. As examples ofsuch the heating method, there are a radiant heating method using ahalogen lamp, a heat conduction method using a heater, and a heatconvection method using hot air. These methods are selectively useddepending on kinds or situations of process.

[0006]FIG. 1 is a schematic view of a conventional apparatus forgenerating ICP. Referring to FIG. 1, a chamber 10 provides a hermeticalspace for performing a plasma process. The hermetical space is dividedinto three spaces horizontally by an antenna plate 20 and a gasdistribution plate 30. The gas distribution plate 30 is placed below theantenna plate 20.

[0007] A plurality of injecting holes are formed in the gas distributionplate 30. Between the antenna plate 20 and the gas distribution plate30, there is disposed a reaction gas supplying port (not shown). Areaction gas introduced through the reaction gas supplying port to aspace between the antenna plate 20 and the gas distribution plate 30 isinjected through the injecting holes of the gas distribution plate 30 toa lower space of the gas distribution plate 30. At the lower space ofthe gas distribution plate 30, there is formed a reaction gasdischarging port (not shown). The reaction gas injected to the lowerspace of the gas distribution plate 30 is converted into a plasma stateby an electromagnetic field formed by an RF antenna 25 mounted on theantenna plate 20. Reflectance of RF power applied to the RF antenna 25is minimized through a matching box 50.

[0008] Since the gas distribution plate 30, the inner wall of thechamber 10 and the antenna plate 20 are exposed to the plasma and theby-product such as polymer is deposited to surfaces of the inner walland the antenna plate 20 during the process. The deposited by-product isserved as a source that generates undesirable particles during theprocess. Therefore, in order to reduce the deposition of the by-product,a plurality of halogen lamps 45 for heating the elements of the chamber10, such as the gas distribution plate 30, and the inner wall of thechamber 10 are disposed over the antenna plate 20. The halogen lamp 45is fixed by a lamp supporting plate 40.

[0009] If the halogen lamp 45 is excessively apart from the antennaplate 20, an intensity of the light arrived at the antenna plate 20 israpidly reduced. Therefore, there occurs a problem in that the gasdistribution plate 30 is not sufficiently heated. This is because theintensity of light arrived at the antenna plate 20 is inverselyproportional to a square of a distance between the antenna plate 20 andthe halogen lamp 45. If the halogen lamp 45 is disposed to be adjacentto the antenna plate 20 in order to prevent the foregoing problem, an RFnoise phenomenon occurs due to a high frequency generated from the RFantenna 25. Further, there is a problem that a distribution of heatarrived at the antenna plate 20 and the gas distribution plate 30 is notuniform.

[0010] Therefore, in order to equally heat the gas distribution plate 30while the halogen lamp 45 is not influenced by the RF noise, the halogenlamp 45 has to be apart from the antenna plate 20 at a proper distance.However, in this case, the gas distribution plate 30 is heated only at atemperature of 70˜80° C. Therefore, there is a problem that the gasdistribution plate 30 is not sufficiently heated.

[0011] According to the conventional apparatus for generating ICP, inorder to sufficiently heat the elements within the chamber 10, such asthe gas distribution plate 30, and the inner wall of the chamber 10without the generation of the RF noise phenomenon, the halogen lamp 45has to be apart from the antenna plate 20 at a long distance and thenumber of halogen lamps 45 also has to be increased. However, in thiscase, there are some problems that an operation and an installation ofthe halogen lamp 45 are complicated and fabrication and operation costsare increased.

SUMMARY OF THE INVENTION

[0012] Therefore, it is an object of the present invention to provide anapparatus for generating ICP, which is capable of heating the elementsin the chamber and inner wall of the chamber without generation of theRF noise.

[0013] To achieve an aforementioned object of the present invention,there is provided an apparatus for generating ICP, the apparatuscomprising a chamber providing a hermetical space; an antenna platedisposed to horizontally divide the hermetical space; a gas distributionplate disposed to horizontally divide a lower space of the antenna plateand having a plurality of injecting holes; a reaction gas supplying portdisposed at a space between the antenna plate and the gas distributionplate so as to inject a reaction gas through the injecting holes of thegas distribution plate to a lower space of the gas distribution plate; areaction gas discharging port disposed to discharge the reaction gasinjected to the lower space of the gas distribution plate; an RF antennafor forming plasma at the lower space of the gas distribution plate,which is mounted on the antenna plate; a heating plate for heating thechamber, which is disposed to horizontally divide an upper space of theantenna plate and which has a plurality of air holes; a heattransferring gas supplying port disposed at an upper space of theheating plate so as to inject a heat transferring gas through the airholes of the heating plate to a space between the heating plate and theantenna plate; and a heat transferring gas discharging port disposed todischarge the heat transferring gas injected to the space between theheating plate and the antenna plate.

[0014] Preferably, the heating plate is comprised of a two-layeredaluminum plate having a recessed groove at a junction portiontherebetween, a hot wire disposed in the recessed groove along therecessed groove, and an insulating member enclosing the hot wire.Alternatively, the heating plate is comprised of a two-layered aluminumplate, a plate type hot wire interposed between the two layers of thealuminum plate, and an insulating member enclosing the hot wire.

[0015] Meanwhile, it is preferable that the gas distribution plate isdisposed according to an equation as follows;${{10 \times \left( \frac{ɛ_{air}}{ɛ\quad p} \right) \times D} \prec d \prec {100 \times \left( \frac{ɛ_{air}}{ɛ_{p}} \right) \times D}},$

[0016] where d is a distance between the heating plate and the antennaplate, ε_(p) is an entire dielectric of the antenna plate and the gasdistribution plate, ε_(air) is a dielectric of air between the heatingplate and the antenna plate, and D is an entire thickness of the antennaplate and the gas distribution plate.

[0017] Further, it is preferable that the air holes of the heating plateare disposed in two concentric circles respectively having radiusesr_(a) and r_(b) from a center of the heating plate, and a differencebetween the number of air holes disposed in the radius r_(a) and thenumber of air holes disposed between the radiuses r_(b)-r_(a) is in anextent of 20%.

[0018] Preferably, the air holes of the heating plate is disposedaccording to an equation as follows:${\left\lbrack {\left( \frac{r_{b}}{r_{a}} \right)^{2} - 1} \right\rbrack \times 0.8} \leq \frac{N_{b - a}}{N_{a}} \leq {\left\lbrack {\left( \frac{r_{b}}{r_{a}} \right)^{2} - 1} \right\rbrack \times 1.2}$

[0019] where N_(a) is the number of the air holes disposed in the radiusr_(a), and N_(b-a) is the number of the air holes disposed in the radiusr_(b)-r_(a).

[0020] Further, it is preferable that the apparatus further comprisesflow-meters disposed at each of the heat transferring gas supplying anddischarging ports to be capable of controlling a flow rate of thetransferring gas, and a feedback device comparing a temperature of theantenna plate with a desired reference temperature and outputting acontrolling signal to the flow-meters so as to maintain the temperatureof the antenna plate at the desired reference temperature.

[0021] Preferably, the apparatus further comprises a heat insulatingplate and a water cooling line disposed at the inner wall of the chamberlocated at an upper portion of the antenna plate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above objects and other advantages of the present inventionwill become more apparent by describing in detail preferred embodimentsthereof with reference to the adhered drawings in which:

[0023]FIG. 1 is a schematic view of a conventional apparatus forgenerating ICP;

[0024]FIG. 2 is a schematic view of an apparatus for generating the ICPaccording to an embodiment of the present invention;

[0025]FIGS. 3a to 3 e are views showing a heating plate of FIG. 2; and

[0026]FIG. 4 is a circuit diagram showing an equivalent circuit betweenthe heating plate and a gas distribution plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Now, preferred embodiments of the present invention will bedescribed in detail with reference to the annexed drawings.

[0028]FIG. 2 is a schematic view of an apparatus for generating an ICPaccording to an embodiment of the present invention. Referring to FIG.2, a chamber 110 is provided as a hermetical space for performing aplasma process. The hermetical space is divided into three spaceshorizontally by an antenna plate 120 and a gas distribution plate 130.The gas distribution plate 130 is located below the antenna plate 120.The antenna plate 120 and the gas distribution plate 130 are made ofceramic.

[0029] A plurality of injecting holes are formed in the gas distributionplate 130. Between the antenna plate 120 and the gas distribution plate30, there is disposed a reaction gas supplying portion (not shown). Areaction gas supplied through the reaction gas supplying port to a spacebetween the antenna plate 120 and the gas distribution plate 130 isinjected through the injecting holes of the gas distribution plate 130to a lower space of the gas distribution plate 130.

[0030] At the lower space of the gas distribution plate 130, there isarranged a reaction gas discharging port (not shown). The reaction gasinjected to the lower space of the gas distribution plate 130 isconverted into a plasma state by electromagnetic field formed by a RFantenna 125 mounted on the antenna plate 120. Reflectance of RF powerapplied to the RF antenna 125 is minimized through a matching box 150disposed at an outer upper portion of the chamber 110.

[0031] In order to reduce deposition of a by-product in the chamber 110,there is provided a heating plate 140 for heating elements of thechamber 110, such as the gas distribution plate 130, and inner wall ofthe chamber 110. The heating plate 140 is disposed to horizontallydivide an upper space of the antenna plate 120, and it has a pluralityof air holes H.

[0032] At an upper space of the heating plate 140, there is arranged aheat transferring gas supplying port 142. A heat transferring gasintroduced through the heat transferring gas supplying port 142 into theupper space of the heating plate 142 is injected through the air holes Hto a space between the heating plate 140 and the antenna plate 120. Atthe space between the heating plate 140 and the antenna plate 120, thereis arranged a heat transferring gas discharging port 144 through whichthe heat transferring gas between the heating plate 140 and the antennaplate 120 is discharged.

[0033] Since heat generated from the heating plate 140 is transferred tothe antenna plate 120 by the heat transferring gas, a temperature of theantenna plate 120 is influenced by pressure and flow rate of the heattransferring gas between the heating plate 140 and the antenna plate120. Therefore, at the supplying port 142 and the discharging port ofthe heat transferring gas, there are respectively disposed flow-meters142 a and 144 a which are capable of controlling the flow rate of thetransferring gas. And also, at the space between the heating plate 140and the antenna plate 120, there is disposed a feedback device (notshown) for controlling the pressure and the flow rate of the flowingheat transferring gas. The feedback device compares a temperature of theantenna plate 120 with a predetermined temperature so as to output acontrolling signal to each of the flow-meter 142 a, 144 a, which isadapted to constantly maintain the temperature of the antennal plate 120at a desired reference temperature.

[0034] Since a temperature around the heating plate 140 is increased toabout 200° C., a heat insulating plate 117 and a water cooling line 115are disposed at the inner wall of the chamber 110 located at an upperportion of the antenna plate 120 in consideration of safety of anoperator and an erroneous operation of the matching box 150.

[0035]FIGS. 3a to 3 e are views showing the heating plate 140. Herein,FIGS. 3a to 3 c are plan views respectively showing three types of theheating plates, and FIGS. 3d and 3 e are cross-sectional views showingtwo types of the heating plates taken along a line A-A′ of FIG. 3a.

[0036] Referring to FIGS. 3a to 3 d, the heating plate 140 is comprisedof a two-layered aluminum plate 140 a served as an RF shield and havinghigh heat conductivity, a hot wire 140 c as a heat radiating mean, andan insulating member 140 d enclosing the hot wire 140 c. The two-layeredaluminum plate 140 a has a recessed groove at a junction portiontherebetween and is electrically grounded. The hot wire 140 c isdisposed around the air holes H along the recessed groove.Alternatively, a plate type hot wire 140 c may be used, as shown in FIG.3e. In this case, it is not necessary to provide the recessed groove atthe aluminum plate 140 a. As shown in FIGS. 3a to 3 c, the hot wire 140c may be aligned in various types.

[0037] The air holes H are disposed in concentric circles C1 and C2respectively having radiuses r_(a) and r_(b) (r_(a)<r_(b)). A differencebetween the number of air holes disposed in the circle C1 and the numberof air holes disposed between the circles C1 and C2 is in an extent of20%. When the air holes H are distributed in this way, as describedabove, the heat is equally transferred to the gas distribution plate130.

[0038] For example, assuming that the number of the air holes H disposedin the radius r_(a) is N_(a), and the number of the air holes H disposedin the radius r_(b)-r_(a) is N_(b-a), it is preferable that the numbersN_(a) and N_(b-a) are defined according to an equation 1, as follows:$\begin{matrix}{{\left\lbrack {\left( \frac{r_{b}}{r_{a}} \right)^{2} - 1} \right\rbrack \times 0.8} \leq \frac{N_{b - a}}{N_{a}} \leq {\left\lbrack {\left( \frac{r_{b}}{r_{a}} \right)^{2} - 1} \right\rbrack \times 1.2}} & \left\lbrack {{Equation}\quad 1} \right\rbrack\end{matrix}$

[0039]FIGS. 3a to 3 c shows a result that the air holes H are aligned oncircumferences of the circles C1 and C2, wherein the radius r_(a) is 8,the radius r_(b) is 12, the number N_(a) is 8 and the number N_(b-a) is8. The air holes H are disposed on axes that equally divide the circlesC1 and C2 into eight regions. Herein, the number N_(b-a) is calculatedby an equation 2, as follows: $\begin{matrix}{N_{b - a} = {{\left\lbrack {\left( \frac{r_{b}}{r_{a}} \right)^{2} - 1} \right\rbrack \times 0.8 \times N_{a}} = 8}} & \left\lbrack {{Equation}\quad 2} \right\rbrack\end{matrix}$

[0040]FIG. 4 shows an equivalent circuit between the heating plate 140and the gas distribution plate 130. Referring to FIG. 4, assuming that afrequency of the RF power is W_(RF), an entire dielectric of the antennaplate 120 and the gas distribution plate 130 is ε_(p), and an entirethickness of the antenna plate 120 and the gas distribution plate 130 isD, if a dielectric of the reaction gas between the antenna plate 120 andthe gas distribution plate 130 is ignored, a plasma impedance Z_(p) iscalculated by an equation 3, as follows: $\begin{matrix}{{\left. Z_{p} \right| = \frac{1}{W_{RF} \times C_{p}}},{C_{p} = \frac{ɛ_{p} \times A}{D}}} & \left\lbrack {{Equation}\quad 3} \right\rbrack\end{matrix}$

[0041] Further, assuming that an dielectric of the heat transferring gasbetween the heating plate 140 and the antenna plate 120 is ε_(air), anda distance between the heating plate 140 and the antenna plate 120 is d,an impedance Z_(air) of the heat transferring gas is calculated by anequation 4, as follows: $\begin{matrix}{{\left| Z_{air} \right| = \frac{1}{W_{RF} \times C_{air}}},{C_{air} = \frac{ɛ_{air} \times A}{d}}} & \left\lbrack {{Equation}\quad 4} \right\rbrack\end{matrix}$

[0042] Therefore, it may be shown as follows:|Z_(p)/Z_(air)|=C_(air)/C_(p)=(ε_(air)/ε_(p))×(D/d). Since the less avalue Z_(p)/Z_(air) is smaller than 1, the more an efficiency of the RFpower used for generating the plasma is increased, preferably, it isshown as follows: d>>(ε_(air)/ε_(p)) * D in order to efficientlygenerate the plasma. However, since the distance d cannot beindefinitely increased, it is preferably that the distance d iscalculated by an equation 5, as follows: $\begin{matrix}{{{10 \times \left( \frac{ɛ_{air}}{ɛ\quad p} \right) \times D} \prec d \prec {100 \times \left( \frac{ɛ_{air}}{ɛ_{p}} \right) \times D}},} & \left\lbrack {{Equation}\quad 5} \right\rbrack\end{matrix}$

[0043] where it may be shown as follows: D<d<10*D, since the ε_(p) isabout 10 and the ε_(air) is about 1.

[0044] According to the apparatus for generating the ICP, as describedabove, the elements in the chamber 110, such as the gas distributionplate 130, and the inner wall of the chamber 110 can be heated up to atemperature of about 200° C., thereby reducing the adhesion of theby-product served as the source generating the undesirable particles. Inaddition, since the hot wire 140 c having a longer life span than thehalogen lamp 45 is used as heat radiating means, the life span of theapparatus is also increased. And since the hot wire 140 c is lessinfluenced by the RF noise than the halogen lamp 45 and the aluminumplate 140 a also functions as the RF shield, the influence by the RFnoise is remarkably reduced.

[0045] While the present invention has been described in detail, itshould be understood that various changes, substitutions and alterationscan be made hereto without departing from the spirit and scope of theinvention as defined by the appended claims.

What is claimed is:
 1. An apparatus for generating ICP, comprising: achamber providing a hermetical space; an antenna plate disposed tohorizontally divide the hermetical space; a gas distribution platedisposed to horizontally divide a lower space of the antenna plate andhaving a plurality of injecting holes; a reaction gas supplying portdisposed at a space between the antenna plate and the gas distributionplate so as to inject a reaction gas through the injecting holes of thegas distribution plate to a lower space of the gas distribution plate; areaction gas discharging port disposed to discharge the reaction gasinjected to the lower space of the gas distribution plate; an RF antennafor forming plasma at the lower space of the gas distribution plate,which is mounted on the antenna plate; a heating plate for heating thechamber, which is disposed to horizontally divide an upper space of theantenna plate and which has a plurality of air holes; a heattransferring gas supplying port disposed at an upper space of theheating plate so as to inject a heat transferring gas through the airholes of the heating plate to a space between the heating plate and theantenna plate; and a heat transferring gas discharging port disposed todischarge the heat transferring gas injected to the space between theheating plate and the antenna plate.
 2. The apparatus of claim 1,wherein the gas distribution plate is disposed according to an equationas follows;${{10 \times \left( \frac{ɛ_{air}}{ɛ\quad p} \right) \times D} \prec d \prec {100 \times \left( \frac{ɛ_{air}}{ɛ_{p}} \right) \times D}},$

wherein d is a distance between the heating plate and the antenna plate,ε_(p) is an entire dielectric of the antenna plate and the gasdistribution plate, ε_(air) is a dielectric of air between the heatingplate and the antenna plate, and D is an entire thickness of the antennaplate and the gas distribution plate.
 3. The apparatus of claim 1,wherein the air holes of the heating plate are disposed in twoconcentric circles respectively having radiuses r_(a) and r_(b) from acenter of the heating plate, and a difference between the number of airholes disposed in the radius r_(a) and the number of air holes disposedbetween the radiuses r_(b)-r_(a) is in an extent of 20%.
 4. Theapparatus of claim 3, wherein the air holes of the heating holes arealigned to be apart from each other at regular intervals.
 5. Theapparatus of claim 3, wherein the air holes of the heating plate isdisposed according to an equation as follows:${\left\lbrack {\left( \frac{r_{b}}{r_{a}} \right)^{2} - 1} \right\rbrack \times 0.8} \leq \frac{N_{b - a}}{N_{a}} \leq {\left\lbrack {\left( \frac{r_{b}}{r_{a}} \right)^{2} - 1} \right\rbrack \times 1.2}$

where N_(a) is the number of the air holes disposed in the radius r_(a),and N_(b-a) is the number of the air holes disposed in the radiusr_(b)-r_(a).
 6. The apparatus of claim 1, further comprising flow-metersdisposed at each of the heat transferring gas supplying and dischargingports to be capable of controlling a flow rate of the transferring gas,and a feedback device comparing a temperature of the antenna plate witha desired reference temperature and outputting a controlling signal tothe flow-meters so as to maintain the temperature of the antenna plateat the desired reference temperature.
 7. The apparatus of claim 1,wherein the heating plate is comprised of a two-layered aluminum platehaving a recessed groove at a junction portion therebetween, a hot wiredisposed in the recessed groove along the recessed groove, and aninsulating member enclosing the hot wire.
 8. The apparatus of claim 1,wherein the heating plate is comprised of a two-layered aluminum plate,a plate type hot wire interposed between the two layers of the aluminumplate, and an insulating member enclosing the hot wire.
 9. The apparatusof claim 1, further comprising a heat insulating plate and a watercooling line disposed at the inner wall of the chamber located at anupper portion of the antenna plate.